Deprecate wxWindow::MakeModal().

Using this function was never the right way to show a modal window and it
didn't really work correctly. Instead of futilely trying to fix it, just
deprecate it.

Closes #1561.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70838 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/window.h

@@ -623,9 +623,10 @@ public:
 
     bool HasExtraStyle(int exFlag) const { return (m_exStyle & exFlag) != 0; }
 
+#if WXWIN_COMPATIBILITY_2_8
         // make the window modal (all other windows unresponsive)
-    virtual void MakeModal(bool modal = true);
-
+    wxDEPRECATED( virtual void MakeModal(bool modal = true) );
+#endif
 
     // (primitive) theming support
     // ---------------------------